Self-priming pump or submersible pump, which one suits your application? The answer depends on factors such as installation type, maintenance access, solids handling capability and Total Cost of Ownership. In this article, we compare both pump types on the criteria that matter in practice, so you can make an informed decision.
Quick answer: when to choose which pump?
Choose a self-priming pump if you want to install the pump above ground and dry, if ease of maintenance is important, or if you work with fluctuating liquid levels. The pump independently evacuates air from the suction line and does not need to be submerged in the liquid.
Choose a submersible pump if the pump is placed in the liquid, above-ground space is limited, or if the investment in a dry-installed pump chamber is not desired. Keep in mind that maintenance must then take place in the sump or below liquid level.
How does a self-priming pump work vs a submersible pump?
A self-priming centrifugal pump is installed above liquid level. The pump creates a pressure drop at the suction side, causing atmospheric pressure to push the liquid into the pump via the suction line. After the initial fill, the pump can automatically re-prime when interrupted.
A submersible pump is placed directly in the liquid — usually in a wet well or pump sump. The motor is housed in a watertight casing. Because the pump is positioned below liquid level, priming is not required.
Comparison table: the key differences
| Criterion | Self-priming pump | Submersible pump |
|---|---|---|
| Installation | Above ground, dry installed | In the liquid (wet well) |
| Priming | Self-priming via suction line | Not required (submerged in medium) |
| Maintenance | Accessible above ground | In the sump, often below liquid level |
| Trouble shooting | Easy through suction- and discharge readings | Difficult – only discharge pressure can be monitored |
| Solids handling | Up to 100 mm (depending on series) | Varies by model |
| Safety | No confined space required | Confined space entry required |
| Motor cooling | Air-cooled or separate | Cooled by surrounding medium |
| Flexibility | High (mobile/stationary) | Limited to fixed location in sump |
| Noise | Audible (above ground) | Muffled (below liquid level) |
Advantages and disadvantages per pump type
Self-priming pump
The main advantages are accessibility for maintenance, flexibility in installation and the ability to reach the pump safely and dry. A service-friendly design — with inspection cover and shimless adjustment — reduces maintenance time and lowers downtime. Disadvantage: above-ground space is required and the suction line must be correctly sized to bridge the suction lift.
Submersible pump
A submersible pump takes up little space above ground and is relatively quiet in operation. Purchase costs are sometimes lower. Disadvantage: maintenance takes place in the sump, requiring additional safety measures (confined space, lifting facilities). Failures therefore often lead to longer downtime and higher maintenance costs.
Maintenance and Total Cost of Ownership compared
The purchase price is only one part of the total cost. In practice, maintenance costs, downtime and service life determine a large part of the Total Cost of Ownership (TCO).
With a self-priming pump, maintenance is simpler and faster to perform. Components are accessible without hoisting the pump from a sump. This translates into shorter maintenance stops and lower labour costs over the service life. With a submersible pump, maintenance operations are more complex: the pump must be raised, cleaned and replaced after service.
Want to learn more about the total cost structure? Read the article on costs and TCO of self-priming pumps.
Which pump for which application?
| Application | Recommendation | Explanation |
|---|---|---|
| Sewage pump station (permanent) | Self-priming | Safe maintenance, lower TCO long-term |
| Temporary construction dewatering | Self-priming (mobile) | Quickly deployable, flexibly relocatable |
| Small basement sump | Submersible pump | Limited space, simple installation |
| Industrial wastewater | Self-priming | Service-friendly with solids handling requirements |
| Flood control | Self-priming | High flow rates, above-ground access |
Not sure which pump best suits your situation? Use the selection guide by application or view the overview of self-priming pumps.
Frequently asked questions
Yes. Self-priming pumps such as the Super T-Series® handle solids up to 76 mm thanks to the Eradicator® system. The solids handling capability depends on the chosen series and configuration. Some PAV series self priming pumps can even handle solids up to 100 mm
In purchase sometimes yes, but over the full service life not necessarily. The TCO of a self-priming pump is often lower due to simpler maintenance and shorter downtime.
Then a submersible pump may be an option. But also consider a compact above-ground pump station — the advantages of above-ground installation (safety, maintenance) are then preserved.
Not sure which pump is the best fit? Our pump specialists will help you choose based on your application details. Contact us for obligation-free advice.
